Fixed bug with function return and added recursive example

3 files changed, 48 insertions, 40 deletions

diff --git a/src/.vscode/launch.json b/src/.vscode/launch.json
index bc86f64..1008b15 100644
--- a/src/.vscode/launch.json
+++ b/src/.vscode/launch.json
@@ -23,7 +23,7 @@
             "request": "launch",
             "mainClass": "Compiler.Language",
             "projectName": "src_1da2a030",
-            "args": "examples/example.ft -c -e"
+            "args": "examples/recursive.ft -c -e"
         }
     ]
 }
\ No newline at end of file
diff --git a/src/Compiler/Parser.java b/src/Compiler/Parser.java
index c7b0165..0ac91d6 100644
--- a/src/Compiler/Parser.java
+++ b/src/Compiler/Parser.java
@@ -13,6 +13,7 @@ public class Parser {
     private int currentToken = 0;
     private final Map<String,String> definedVars = new HashMap<>();
     List<Statement> statements =  new ArrayList<>();
+    private boolean foundReturn;
 
     /**
      * Constructor of a parser object
@@ -48,7 +49,7 @@ public class Parser {
         if(matchAndAdvance(TokenType.PROGRAM)){
             matchOrError(TokenType.IDENTIFIER, "Expected program name");
             Token programname = getPreviousToken();
-            Statement block = blockStatement(false);
+            Statement block = blockStatement();
             matchOrError(TokenType.PROGRAM,"Programs must end in 'program'");
             matchOrError(TokenType.IDENTIFIER,"Expected program name");
 
@@ -80,7 +81,7 @@ public class Parser {
 
             //Add function name to the list of defined values
             definedVars.put(name.text, "function");
-            matchOrError(TokenType.LEFT_PAREN, "Expected '(");
+            matchOrError(TokenType.LEFT_PAREN, "Expected '(' in function definition");
             List<Expression> arguments=new ArrayList<>();
             List<String> types = new ArrayList<>();
 
@@ -96,11 +97,13 @@ public class Parser {
                     }
                     arguments.add(expression());
                 } while(matchAndAdvance(TokenType.COMMA));
-                matchOrError(TokenType.RIGHT_PAREN, "Expected ')'");
+                matchOrError(TokenType.RIGHT_PAREN, "Expected ')' in function definition");
+            }
+            foundReturn=false;
+            Statement block = blockStatement();
+            if(isfunction&&!foundReturn){
+                throw error(name, "Function must contain a return statement");
             }
-
-            Statement block = blockStatement(isfunction);
-
             //Add the function declaration to the start of the list of statements
             statements.add(0,new Statement.FunctionDeclaration(name,types,returntype));
             return new Statement.Function(name,block,arguments,types,returntype);
@@ -225,7 +228,7 @@ public class Parser {
      * @return A statement representing the array declaration
      */
     private Statement arrayDeclaration(String type){
-        matchOrError(TokenType.LEFT_PAREN,"Expected ')'");
+        matchOrError(TokenType.LEFT_PAREN,"Expected ')' for array definition");
 
         //Extract the size of the array
         List<Expression> dimensions = new ArrayList<>();
@@ -236,9 +239,9 @@ public class Parser {
             dimensions.add(dimension);
         } while(matchAndAdvance(TokenType.COMMA));
 
-        matchOrError(TokenType.RIGHT_PAREN, "Expected ')'");
-        matchOrError(TokenType.DEFINE, ":: Required for variable definition");
-        matchOrError(TokenType.IDENTIFIER,"Expected variable name.");
+        matchOrError(TokenType.RIGHT_PAREN, "Expected ')' for array definition");
+        matchOrError(TokenType.DEFINE, ":: Required for array definition");
+        matchOrError(TokenType.IDENTIFIER,"Expected array name.");
         Token varName = getPreviousToken();
 
         //Ensure that a variable with the same name has not been defined
@@ -255,8 +258,7 @@ public class Parser {
      * @param isFunction whether the block is for a function and so must contain a return statement
      * @return a statement representing a block
      */
-    private Statement blockStatement(boolean isFunction){
-        boolean hasReturn=false;
+    private Statement blockStatement(){
         List<Statement> statements = new ArrayList<>();
 
         //Match statement until an end or else token has been reached
@@ -266,15 +268,8 @@ public class Parser {
                 throw error(getCurrentToken(),"end missing from block");
             }
             Statement statement = statement();
-            if(statement.getStatmentType()=="return"){
-                hasReturn=true;
-            }
             statements.add(statement);
         }
-        //Ensure that a function block contains a return statement
-        if(isFunction&&!hasReturn){
-            throw error(getPreviousToken(), "Function must contain a return statement");
-        }
         return new Statement.BlockStatement(statements);
     }
 
@@ -289,7 +284,7 @@ public class Parser {
         //Get the list of printed values
         while(matchAndAdvance(TokenType.COMMA)){
             if(checkEOF()){
-                throw error(getCurrentToken(),"reached end of file");
+                throw error(getCurrentToken(),"reached end of file scanning print statement");
             }
             Expression expr = expression();
             exprList.add(expr);
@@ -303,20 +298,18 @@ public class Parser {
      */
     private Statement ifStatement(){
         Expression condition = expression();
-        if(matchOrError(TokenType.THEN, "then expected after if statement")){
-            //Extract if block
-            Statement ifBlock = blockStatement(false);
-            Statement elseBlock=null;
+        matchOrError(TokenType.THEN, "then expected after if statement");
+        //Extract if block
+        Statement ifBlock = blockStatement();
+        Statement elseBlock=null;
             
-            //Extract else block if required
-            if(matchAndAdvance(TokenType.ELSE)){
-                elseBlock=blockStatement(false);
-            }
-            matchOrError(TokenType.IF, "If statements end with if");
-            Statement ifstatement = new Statement.IfStatement(condition, ifBlock,elseBlock);
-            return ifstatement;
+        //Extract else block if required
+        if(matchAndAdvance(TokenType.ELSE)){
+            elseBlock=blockStatement();
         }
-        return null;
+        matchOrError(TokenType.IF, "If statements end with if");
+        Statement ifstatement = new Statement.IfStatement(condition, ifBlock,elseBlock);
+        return ifstatement;
     }
 
     /**
@@ -329,17 +322,17 @@ public class Parser {
             return whileStatement();
         }
         Expression variable =expression();
-        matchOrError(TokenType.EQUALS, "'=' missing");
+        matchOrError(TokenType.EQUALS, "'=' missing from do statement assignment");
 
         //Extract start, stop, and step variables
         Expression start = expression();
-        matchOrError(TokenType.COMMA, " use ',' between values");
+        matchOrError(TokenType.COMMA, " use ',' between values in do statement");
         Expression stop = expression();
         Expression step = null;
         if(matchAndAdvance(TokenType.COMMA)){
            step = expression();
         }
-        Statement codeBlock = blockStatement(false);
+        Statement codeBlock = blockStatement();
         matchOrError(TokenType.DO, "Do statements end with do");
         return new Statement.DoStatement(variable, start, stop, step,codeBlock);
 
@@ -351,10 +344,10 @@ public class Parser {
      */
     private Statement whileStatement(){
         //Extract condition
-        matchOrError(TokenType.LEFT_PAREN, " missing '(' for do statement condition");
+        matchOrError(TokenType.LEFT_PAREN, " missing '(' for do while statement condition");
         Expression condition = expression();
-        matchOrError(TokenType.RIGHT_PAREN, " missing ')' for do  condition");
-        Statement codeBlock = blockStatement(false);
+        matchOrError(TokenType.RIGHT_PAREN, " missing ')' for do while condition");
+        Statement codeBlock = blockStatement();
         matchOrError(TokenType.DO, "Do while statements end with do");
         return new Statement.DoWhileStatement(condition,codeBlock);
     }
@@ -364,6 +357,7 @@ public class Parser {
      * @return a return statement object
      */
     private Statement returnStatement(){
+        foundReturn=true;
         Expression returnValue = expression();
         return new Statement.ReturnStatement(returnValue);
     }
@@ -543,7 +537,7 @@ public class Parser {
         //Parse bracketed expressions
         if (matchAndAdvance(TokenType.LEFT_PAREN)){
             Expression expr = expression();
-            matchOrError(TokenType.RIGHT_PAREN,"Expected ')'");
+            matchOrError(TokenType.RIGHT_PAREN,"Expected ')' after bracketed expression");
             return new Expression.BracketedExpression(expr);
         }
         //Throw an error if the expression was not recognised
diff --git a/src/examples/recursive.ft b/src/examples/recursive.ft
new file mode 100644
index 0000000..d6f7a69
--- /dev/null
+++ b/src/examples/recursive.ft
@@ -0,0 +1,14 @@
+program recursive
+int::value
+int::final
+value=5
+final=factorial(value)
+print*,"The factorial of ",value," is ",final
+end program recursive
+
+function int factorial(int x)
+if x==1 then
+return 1
+end if 
+return x*factorial(x-1)
+end
\ No newline at end of file